From 3f01f5296ec2d146f92bcc479a5bade9e898fc40 Mon Sep 17 00:00:00 2001 From: Bill Schmidt Date: Tue, 27 May 2014 15:57:51 +0000 Subject: [PATCH] Correct type used for VADD_SPLAT optimization on PowerPC In PPCISelLowering.cpp: PPCTargetLowering::LowerBUILD_VECTOR(), there is an optimization for certain patterns to generate one or two vector splats followed by a vector add or subtract. This operation is represented by a VADD_SPLAT in the selection DAG. Prior to this patch, it was possible for the VADD_SPLAT to be assigned the wrong data type, causing incorrect code generation. This patch corrects the problem. Specifically, the code previously assigned the value type of the BUILD_VECTOR node to the newly generated VADD_SPLAT node. This is correct much of the time, but not always. The problem is that the call to isConstantSplat() may return a SplatBitSize that is not the same as the number of bits in the original element vector type. The correct type to assign is a vector type with the same element bit size as SplatBitSize. The included test case shows an example of this, where the BUILD_VECTOR node has a type of v16i8. The vector to be built is {0, 16, 0, 16, 0, 16, 0, 16, 0, 16, 0, 16, 0, 16, 0, 16}. isConstantSplat detects that we can generate a splat of 16 for type v8i16, which is the type we must assign to the VADD_SPLAT node. If we do not, we generate a vspltisb of 8 and a vaddubm, which generates the incorrect result {16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16}. The correct code generation is a vspltish of 8 and a vadduhm. This patch also corrected code generation for CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll, which had been marked as an XFAIL, so we can remove the XFAIL from the test case. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209662 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll | 1 - 1 file changed, 1 deletion(-) (limited to 'test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll') diff --git a/test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll b/test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll index 00a402e0e4..8802b97d2a 100644 --- a/test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll +++ b/test/CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll @@ -1,6 +1,5 @@ ; RUN: llc < %s -march=ppc32 -mcpu=g5 | grep vadduhm ; RUN: llc < %s -march=ppc32 -mcpu=g5 | grep vsubuhm -; XFAIL: * define <4 x i32> @test() nounwind { ret <4 x i32> < i32 4293066722, i32 4293066722, i32 4293066722, i32 4293066722> -- cgit v1.2.3